Generic Tool path planning method of T-spline surface CNC milling

Abstract

T-spline is a new surface modeling technology, which has superior advantages in complex shape representation over traditional NURBS and mesh surfaces. However, the research in CAM field is insufficient, which hinders the further promotion of this technology. To fit the complex topology of T-spline surface, a general tool path planning method of T-spline surface CNC milling is proposed based on the commonly used zig-zag or contour-parallel toolpath pattern. This method utilizes the 2-dimensional scallop height model to calculate side step, the iso-scallop height method to generate tool paths, the minimum energy method to smooth them, and Hermite curves to join them as one tool path, which can realize the milling of T-spline surface model with arbitrary topology. Finally, a T-spline CAM prototype system is successfully developed to implement simulation analysis and machining experiments to verify the algorithms above. And the results of simulations and experiments prove this method can generate a smooth tool path with uniform iso-scallop height distribution, short length, smooth corner transition, and one retraction, which can achieve better finish machining effect.